The invention relates to electronic devices, and more particularly to wireless communication.
Demand for wireless information services via cell phones and personal digital assistants (PDAs) is rapidly growing, and techniques and protocols for Internet access have problems such as the delay between requests for web pages which primarily derives from low transmission data rates. Wireless Application Protocol (WAP) attempts to overcome this web page delay problem by transmitting a group of web pages as a deck of cards with each card corresponding to a page of structured content and navigation specifications. Each WAP card has combined the data to be displayed with formatting instructions used in controlling the display of the data and thus causing larger than necessary data downloads for a fixed display format.
An alternative employs broadband wireline Internet access to a local access point and then uses Bluetooth™ wireless connection for the last link to an Internet appliance. The current Bluetooth gross (including overhead) speed of a 1 Mbps channel rate suffices for a 56 kbps wireline (phone line) connection at home. However, with broadband wireline connection to a Bluetooth access point in a home wireless LAN: creates a demand for high data rate Bluetooth.
Bluetooth is a system that operates in the ISM unlicensed band at 2.4 GHz. Slow frequency hopping (1600 hops per second) is used to combat interference and multipath fading: typically 79 channels are available (only 23 channels in France and Spain). The gross bit rate is 1 Mbps (maximal symmetrical data rate of 434 kbps and maximal asymmetrical data rate of 723 kbps), and each hop channel has a bandwidth of 1 MHz. Gaussian frequency shift keying (GFSK) modulation is used. Data packets include 1-2 byte payload headers for information about logical channel and payload length. Forward error correction with ⅔ rate may protect a payload of up to 339 bytes per packet. The link header for a packet has 54 bits and contains control information and active addresses. Each packet typically is transmitted on a different hop frequency (channel). Two communicating Bluetooth devices are termed the master device and the slave device with the downlink being the transmissions from master to slave and the uplink being the transmissions from slave to master.
Another alternative for higher data rate wireless communication is wideband code division multiple access (WCDMA). WCDMA is a proposed standard useful for cellular telecommunications systems with data rates on the order of 144 kbps for high mobility applications, 384 kbps for more pedestrian-class mobility, and 2 Mbps for fixed environments. Quadrature phase shift keying (QPSK) type symbols multiplied by the appropriate spreading-scrambling codes modulating root-raised-cosine pulses are transmitted at a chip rate of 3.84 Mcps.